Worms?

Yesterday I saw one of my Glowlight tetras pick a squiggly white worm (abouth 3/4-inch long) out of the substrate. He tried to eat it, but it was too big for him and he spit it out. Then my largest Lemon tetra took it and swallowed it. For almost a minute afterwards, the Lemon tetra was going beserk and "glancing" off of rocks and plants. Maybe he ate more than he should have...? But then he calmed down right away and he seems fine now.

Then today, while replanting some Glosso stems, I saw another one of these worms squirming through the substrate. I've seen very tiny worms in my tanks before, but these critters are pretty substantial looking. They have some body to them. I assume these worms arrived in my last shipment of plants....?

Anything I should be concerned about?